Silicone surfactants have been reported in the literature. See for example the non-ionic organopolysiloxane surfactants described by Maki and Komori in the journal "Kagaku Kogyo", Vol. 73, No. 6, and in the journal "Hyomen", Vol. 7, No. 11. They are known to be much more effective in lowering surface tension than hydrocarbon surfactants.
As these substances are non-ionic, however, they are of the polyether type. Their dimethylpolysiloxane chain is therefore comparatively short, and their range of application is consequently limited.
Cationic and anionic organopolysiloxane surfactants are also known. See Japanese Patent Kokoku ("Examined Japanese Patent Publication") No. 49-11760. These substances, however, were mixtures of polymers with functional groups at both ends and polymers with functional groups on side chains, or mixtures wherein polymers with functional groups at only one end had been added to the former mixtures, and as a result, these substances did not exhibit good surfactant properties.
In order to widen the range of application of silicone surfactants, therefore, it was necessary to further develop ionic silicone surfactants.
The inventors of this invention carried out intensive research with a view to providing a solution to this problem. Then, using a siloxane which was reactive at one end as starting material to synthesize a surfactant, it was found that an anionic silicone surfactant with extremely good surface tension lowering properties could be obtained, which this led to the present invention.